Greetings are not considered stalker-like behavior. If you started following her around and saying hi, then maybe. How about starting a conversation the next time you see her? Just casually say hey, hows your day going or did you see such and such last night. You can then progress to finding more about her or say you have something to do now, but would love to hang out later. Then ask for her contact info (facebook/number/aim/etc). Hope it helps and good luck!
relax, breathe and oncea day sayinghi is completley fine! hell twice a day is fine but after a few days you need to go further than hi! as for facebook, if you knwo her name add her with a cute message, if not next time you say hi ask her name cos you wanna add her on fbook, shell get the hint
just wait for few days and greet her,sorry just don't take chances you know girls are good at finding out if the guy is really bump into you accidently or he is doing it inteionally (dont be predictble ;)